■基本単体の二面角(その363)

【7】E7格子の場合

  P0(0,0,0,0,0,0,0)

  P1(1,0,0,0,0,0,0)

  P2(1,1/√3,0,0,0,0,0)

  P3(1,1/√3,1/√6,0,0,0,0)

  P4(1,1/√3,1/√6,1/√6,0,0,0,0)

  P5(1,1/√3,1/√6,1/√6,1/√3,0,0)

  P6(1,1/√3,1/√6,1/√6,1/√3,1,0)

  P7(1,1/√3,1/√6,0,0,0,1/2)

超平面をax+by+cz+dw+ev+fu+gt=iとする.

[1]P1P2P3P4P5P6P7を通る超平面:x=1

[2]P0P2P3P4P5P6P7を通る超平面

  i=0

  a+b/√3=0,a=1,b=−√3

  1−1+c/√6=0,c=0

  1−1+c/√6+d/√6=0,d=0,e=0,f=0

1−1+g/2=0,g=0

[3]P0P1P3P4P5P6P7を通る超平面

  i=0,a=0

  b/√3+c/√6=0,b=1,c=−√2

  b/√3+c/√6+d/√6=0,d=0,e=0,f=0

1−1+g/2=0,g=0

[4]P0P1P2P4P5P6P7を通る超平面

  i=0,a=0,b=0

  c/√6+d/√6=0,c=1,d=−1

  e=0,f=0

c/√6+g/2=0,g=−2/√6

[5]P0P1P2P3P5P6P7を通る超平面

  i=0,a=0,b=0,c=0

  d/√6+e/√3=0,d=√2,e=−1

  f=0,g=0

[6]P0P1P2P3P4P6P7を通る超平面

  i=0,a=0,b=0,c=0,d=0

e/√3+f=0,e=√3,f=−1,g=0

[7]P0P1P2P3P4P5P7を通る超平面:u=0

[8]P0P1P2P3P4P5P6を通る超平面:t=0

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  a=(1,0,0,0,0,0,0)

  b=(1,−√3,0,0,0,0,0)

  c=(0,1,−√2,0,0,0,0)

  d=(0,0,1,−1,0,0,−2/√6)

  e=(0,0,0,√2,−1,0,0)

  f=(0,0,0,0,√3,−1,0)

  g=(0,0,0,0,0,1,0)

  h=(0,0,0,0,0,0,1)

を正規化すると

  a=(1,0,0,0,0,0,0)

  b=(1/2,−√3/2,0,0,0,0,0)

  c=(0,1/√3,−√(2/3),0,0,0,0)

  d=(0,0,√6/4,−√6/4,0,0,−1/2)

  e=(0,0,0,√(2/3),−1/√3,0,0)

  f=(0,0,0,0,√3/2,−1/2,0)

  g=(0,0,0,0,0,1,0)

  h=(0,0,0,0,0,0,1)

a・b=1/2

b・c=−1/2

c・d=−1/2

d・e=−1/2

d・h=−1/2

e・f=−1/2

f・g=−1/2

g・h=0

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